The present invention relates to methods and systems for making rigid three-dimensional reinforcement preforms used in resin transfer molding (RTM) and structural reaction injection molding (SRIM) processes for the manufacture of structural composites. The manufacture and use of structural composite materials is becoming increasingly important today, particularly in components for the automotive industry. Structural composites are lighter in weight than conventional steel or metal components and can result in additional advantages, such as allowing fully automated, highly controllable processes, better part-to-part consistency, reduced waste or scrap, and equivalent or increased component performance.
In general, the structural reinforcing preforms are made from a sprayed chopped material, such as glass and carbon fiber, which is held together by a binder and molded into a precise form and shape. The preform in turn is then molded into products, such as composite components (both structural and non-structural) and used in automobiles or other vehicles.
The preform material is chopped and applied along with a powdered binder to a preform screen in a mold using a robotic routine. Positive air flow through the screen holds the chopped material on the screen surface. When the spraying is completed, the mold is closed and the preform is compressed to the desired thickness. Heated air is first drawn through the screen in order to melt the binder. Thereafter, cooled or ambient air is drawn through the preform setting the final shape. Once the preform is completed, it is demolded and transferred to a component mold where the structural component is molded.
Although present automated preform processes and systems have been used to produce satisfactory structural composite products, a need exists to improve the processes and systems, particularly to reduce the cost, increase the output and reliability, and make components of various configurations and thicknesses.